The role of radar in traffic safety enforcement is widespread throughout the United States and the principal tool for police traffic surveillance is Doppler radar. In a police Doppler radar system, an emitted microwave frequency signal is reflected from a target vehicle, causing a change in the frequency of the signal in proportion to a component of the velocity of the target vehicle. The Doppler radar system measures the frequency differential and scales the measurement to miles per hour, for example, in order to display the velocity of the target vehicle to a policeman or other Doppler radar system operator. Using the existing frequency differential scheme, conventional police Doppler radar systems are capable of a high degree of accuracy with regard to vehicle speed measurements in environments having one target vehicle.
It has been found, however, that the existing police Doppler radar systems are not necessarily successful in environments having multiple vehicles in position to reflect the radar signal. In particular, identification of the vehicle whose speed is being displayed when multiple vehicles are in a position to reflect the radar signal has proven difficult due to “look-past error,” which occurs in situations where the intended target vehicle in the foreground has a significantly smaller radar cross-section than an unintended target vehicle in the background. Accordingly, further improvements are warranted in the field of traffic surveillance Doppler radar systems.